Directional drive mechanism



Oct. 13, 1970 H. TIMMER DIRECTIONAL DRIVE MECHANISM 2 Shouts-Sheet 1Filed Feb. 19, 1969 INVENTOR HEN/P) T/MME/P 0a. 13,1910 H. TIMMER3,533,299

DIRECTIONAL DRIVE MECHANISM Filed Feb. 19, 1969 2 Sheets-Sheet 2 g /iwFZHL/ 3,533,299 DIRECTIONAL DRIVE MECHANISM Henry Timmer, Grand Rapids,Mich., assignor to Transign, Inc., Pontiac, Mich. Filed Feb. 19, 1969,Ser. No. 800,514 Int. Cl. B6511 17/02; F16d 11/06; F16h 57/00 US. Cl.74-405 8 Claims ABSTRACT OF THE DISCLOSURE A rotary directional drivetransferring driving torque exclusively in one direction independentlyof the presence or absence of a tendency of the driving and drivenmembers to exhibit relative overrunning rotation from outsideinfluences. An intermediate torque-transfer member is adapted to lock tothe driven member exclusively when driving-director torque is applied bythe driving member.

BACKGROUND OF THE INVENTION Power-transfer mechanisms must frequently beadapted to the application of torque exclusively in one rotationaldirection. This requirement is commonly met by the use of an overrunningclutch or some form of a ratchet drive. An example of such anapplication is the usual starter mechanism, in which torque is appliedfor short periods to provide enough rotation of an internal combustionengine to begin its normal operation. Once the engine begins to run, itsrotational speed is normally in excess of that provided by the starter,and it overruns the starting drive. The characteristic of this form ofmechanism is that the torque is transferred through the starting driveas long as the driven member is not moving faster than the drivingmember in the same direction at the point of interengagement. In mostapplications, this presence or absence of an overrunning conditioncorresponds exactly to the conditions under which torque must besupplied.

Applications are occasionally encountered, however, where the deliveryof torque must not always correspond to the mere presence or absence ofan overrunning condition. One such application is in the mechanism usedfor positioning the scrolls of a destination sign. These signs arecommonly associated with buses, streetcars, and local trains to indicatethe particular destination to passengers about to board. Essentially,these signs include a pair of rollers on which a long strip of fabric iswound in the manner of a scroll. The fabric is printed with a sequenceof destinations, and the sign is equipped with a drive mechanism capableof rotating the scrolls in either direction so that any particularportion of it may be exposed at the viewing point. The driving mechanismobviously must be adapted to move the scrolls in either direction, andit is here that the problem arises. It is common practice to use eithera chain or a geared driving mechanism interrelating the rolls with amanual or powered actuating mechanism, and provisions must necessarilybe made for the fact that at almost all occasions there will be morefabric wound on one roll than on the other. Since the linear velocity ofthe fabric is the same; it is clear that at any given moment there willbe a different angular velocity of one roll than for the other toproduce a given linear velocity of the fabric. This is true regardlessof the direction of rotation that the operator wishes to induce in therolls. With most of the fabric accumulated on one of the scroll rollers,a driving action in either direction will induce a more rapid rate ofrotation of the opposite scroll roller than that of the roller on whichthe bulk of the fabric has accumulated. The design problem confrontingthe engineer at this point is the provision of United States Patent "icea directional drive mechanism that can be associated with each roller sothat power can be delivered from a central point through a gear trainassociating both rollers without inducing a jamming action under anyconditions. It is clear that a mere overrunning mechanism, which wouldinterconnect a driving relationship purely as a function of anoverrunning condition, will not work. Such a mechan ism would induce adriving connection to both rollers at the same time, in which it wouldbe impossible to accommodate a different winding diameter. The US. Pat.No. 3,073,542, issued to John Kaashoek in March of 1960 is an example ofthe form of mechanism referred to in this discussion. The disclosure ofthis application may be considered as an improvement on the Kaashoekmechanism.

SUMMARY OF THE INVENTION The driving mechanism provided by thisinvention has the characteristic of transferring torque as a function ofthe presence or absence of the initial delivery of torque, rather thanin response to the presence or absence of an overrunning condition. Inthe preferred form of this invention, an intermediate member ismechanically interposed between a driving and a driven member, which arecoaxially mounted for both relative and joint rotation. An actuatorcarried by the intermediate member is positioned by the application oftorque from the driving member so that it moves to a position tointersect an abutment on the driven member. Under these conditions, adriving relationship is established through the mechanism for thedelivery of torque in a particular rotational direction. In the absenceof driving torque, the actuator remains in a retracted position clear ofthe abutment, which permits the driven member to rotate independently ofthe intermediate and drive members. A braking mechanism effectivebetween the intermediate and driven members establishes enoughresistance to relative rotation between these components to induce theextension of the actuator into driving position. This same brakingmechanism is also utilized, in the preferred form of the invention, toestablish a resistance to rotation of the roller for the main- 4 tenanceof winding tension in the fabric of a directional sign mechanism so thatthe driven roller will have some degree of pulling action to maintain adesired degree of tautness in the fabric.

DESCRIPTION OF THE DRAWINGS The several features of the invention willbe analyzed in detail through a discussion of the particular embodimentillustrated in the accompanying drawings. In the drawings:

FIG. 1 is a sectional elevation through a destination sign mechanismprovided with the directional drive systems embodying this invention.

FIG. 2 is a sectional view on an enlarged scale on the plane 2-2 of FIG.1.

FIG. 3 is a sectional view on an enlarged scale on the plane 33 of FIG.1.

FIG. 4 is a view illustrating the driving condition of the mechanismshown in FIG. 3.

FIG. 5 is a view illustrating the inactive condition of the mechanismshown in FIG. 3.

FIG. 6 is a view on an enlarged scale, taken on an axial plane, showingthe mounting of the actuator on the intermediate member.

FIG. 7 is a perspective view showing the driven member of the mechanism,on an enlarged scale.

FIG. 8 is a section on the plane 8-8 of FIG. 7.

FIG. 9 is a section on the plane 99 of FIG. 7.

FIG. 10 is an end view on the inside face of the intermediate membershowing the mounting of the actuator.

3 DESCRIPTION OF THE PREFERRED EMBODIMENT The destination sign mechanismshown in FIG. 1 includes a frame generally indicated at providingsupport for the rotatably-mounted rollers 21 and 22. These rollers arein scroll relationship, a long strip of printed fabric presenting signdesignations being wound at opposite ends on these rollers, and trainedfrom the roller 21 around the guide rollers 23 and 24. A light bracket25 provides a convenient mounting platform for bulbs of any desireddescription, and is supported on the rods 26 and 27 secured at oppositeends to the frame structure 20. Tabs as indicated at 28 on the frame 20may be used for mounting the entire assembly in a vehicle. The unit isusually installed in such a position that the space between the guiderollers 23 and 24 is opposite a viewing window in the front or side ofthe vehicle.

Each of the rollers 21 and 22 is equipped with a similar torque-transfermechanism which includes the spur gears 29 and 30, respectively. Theidler gears 31 and 32 ar respectively mounted on stub shafts 33 and 34,and these idlers mesh both with the gears 29 and and with the centralgear 35 appearing most clearly in FIG. 2. The gear 35 and the bevel gear36 are both secured to the tubular member 37 rotatably mounted on theshaft 38, the position of the gears being secured by the set screwsindicated at 39 and 40. The mating bevel gear 41 is secured to the shaft42 rotatably mounted in the bearings 43 and 44 carried by the bracket 45and the frame 20, respectively. The shaft 42 extends out to a sufficientlength to receive the wheel crank 46, with which the sign mechanism isadjusted. The manual torque delivered to the crank wheel 46 is deliveredthrough the gear train and the torque-transfer mechanism associated witheach roller to position the fabric strip carrying the sign indicia.

The selective torque-transfer mechanisms associated with the rollers 21and 22 are both alike, and are shown in FIGS. 3 through 6. The rollerseach includes a tubular member 47 which receives the sign fabric, andopposite end plugs as shown at 48. These end plugs are rotatablyreceived on the shafts 49. FIG. 3 illustrates the driving end of therollers, the opposite end being provided merely with a rotatablemounting of any conveinent description in the frame structure 20.

The power-transfer mechanism shown in FIG. 3 includes the driving gear30 and the intermediate member 50. This member may be considered toinclude the annular cap 51, which completes an embracing relationship ofthe intermediate member about the driven member 52. At this end of therollers, the intermediate member 52 and the end plug 48 are preferablyintegral. The intermediate member 50 is of a cup-shaped configurationproviding the annular rim 53 and the disc-shaped panel 54 generallyperpendicular to the axis of rotation of the assembly. The shaft 49 isnon-rotatable with respect to the l frame structure, by virtue of thereception of the squared end 55 in a similarly-shaped opening in theframe 2 0.

An actuating lever 56 is pivotally mounted on the portion 54 of theintermediate member 50 with the fulcrum pin 57. An offset portion 58 ofthe actuating lever 56 extends through the opening 59 in theintermediate member 50 for engagement with a detent device mountedwithin a recess 61 in the driving gear 30. The detent device appearsmost clearly in FIGS. 4 and 5, and is essentially a leaf spring 62 fixedat one end to the outer face of the gear 30 with the pin 63. Theopposite end of the spring 62 is provided with a portion 64 engageablewith the end 58 of the actuating lever 56. The shape of the portion 64and the portion 58 of the actuating lever 56 is such that a drivingrelationship can only exist when the portion 64 is moving to the leftwith respect to the portion 58, as shown in FIG. 4. Under conditions inwhich the lever portion 58 encounters the portion 64 of the detentmechanism from the opposite direction, the leaf spring 50 will 4 deflectsufliciently to permit the lever portion 58 to pass underneath theportion 64.

When torque is applied through counterclockwise rotation of the gear 30,as shown in FIG. 4, the force applied to the portion 58 by the detentportion 64 will induce a limited rotation of the actuating lever 56about the pin 57 against the restraint of the spring 65. This Springextends to a suitable terminal connection 66 on the portion 54 of theintermediate member 50, and tends to rotate the actuating member 56toward a retracted position in which the end 67 to a point sufficientlyradially inward of the projections 68-71 on the intermediate member 52to clear them. The application of driving torque, however, displaces thelever 56- about the pin 57 to the point that the end 67 assumes aradially outward position where it is capable of intercepting any one ofthe projections 68-71. The engagement of the end 56:: of the lever 56within the pin 56b establishes a limitation to the degree of rotation ofthe lever 56, or any other stop arrangement can be provided to establishthis limitation. Once the limitation to the rotation of the lever 56 hasbeen attained, it forms a rotative interlock between the intermediatemember 50 and the driven member 52. When no torque is applied betweenthe gear 30 and the intermediate member 50, this condition cannot exist,by virtue of the presence of the spring continually urging the actuatinglever 56 to inactive position determined by the pin 560.

It is desirable to establish a minimum degree of resistance to relativerotation between the intermediate member 50 and the driven member 52,and this resistance must be sufiicient to assure that driving torqueapplied by the gear 30 will move the actuating lever 56, rather thanmerely spin the intermediate member 50 out of driving relationship tothe driven member 52. This resistance is established by the breakingaction generated by the bearing ball 72 received within the radialrecess 73 in the intermediate member 52. The spring 74 continually urgesthe bearing ball outward against the rim 53 of the intermediate member,and establishes the desired resistance to relative rotation betweenthese components. Once the driving torque has been established, however,the forces involved are sufficiently large that it is prefarable thatthe projections 68-71 be in the form of inserts of relatively strongmaterial inlaid into the intermediate member 52, and held there by setscrews as indicated at 75-78.

The breaking action provided by the bearing ball 72 has the additionalvalue of providing a predetermined degree of tension in the fabriccarried by the rolls 21 and 22. By securing the intermediate member 50against backrotation with respect to the shaft 49, the bearing member 52will establish the necessary drag on the rollers to establish thetension in the sign fabric. This locking against back-rotation isprovided by the latch assembly shown in FIG. 8. The shaft 49 has atransverse bore 79 receiving the moving latch member 80', which isengageable with the notch 80:: in the intermediate member 50'. A spring81 biases the latch member to the left, as shown in FIG. 8, with the endof the recess 79 being blocked by a portion 82, which can be eithermachined as a part of the transverse bore 79, or staked over as asecondary operation. A retaining screw 83 permits the assembly of thecomponents, and operates as a seat for the spring 81.

The particular embodiments of the present invention which have beenillustrated and discussed herein are for illustrative purposes only andare not ot be considered as a limitation upon the scope of the appendedclaims. In these claims, it is my intent to claim the entire inventiondisclosed herein, except as I am limited by the prior art.

What is claimed is:

1. A directional drive mechanism having coaxial rotary driving anddriver members, wherein the improvement comprises:

an intermediate member rotatably mounted coaxially with said driving anddriven members;

at least one abutment on said driven member;

an actuator mounted on said intermediate member for movement between anactive position engageable with said abutment on relative rotationbetween said driven and intermediate members, and an inactive positionclearing said abutment;

a detent mounted on said driving member and engageable with a portion ofsaid actuator and adapted to apply force thereto exclusively in adirection to urge the same to active position; and

resistance-generating means interengaging said intermediate and drivenmembers and adapted to inhibit relative rotation thereof.

2. A mechanism as defined in claim 1, wherein said driving,intermediate, and driven members are coaxially mounted on a fixed shaft,and said mechanism also ineludes a directional lock limiting rotation ofsaid intermediate member to the driving direction of said drivingmember.

3. A mechanism as defined in claim 1, wherein said actuator is a leverpivotally mounted at an intermediate point thereon on an axis parallelto the axis of rotation of said members, one end of said lever beingengageable with said abutment, and the other end engageable with saiddetent.

4. A mechanism as defined in claim 3, wherein said intermediate memberhas a face perpendicular to the axis thereof, said face having anopening, and said actuator has a portion traversing said opening forengagement with said detent,

5. A mechanism as defined in claim 1, additionally including biasingmeans urging said actuator to inactive position, and wherein saidresistance-generating means produces a torque (opposing relativerotation between said intermediate and driven members) in excess of thetorque produced by the force required to move said actuator to activeposition against said biasing means.

6. A mechanism as defined in claim 5, wherein said intermediate memberhas a cup-shaped configuration having a rim and a portion transverse tothe axis thereof, said driven member abutment extending axially in thespace defined by said rim.

7. A mechanism as defined in claim 6, wherein said resistance-generatingmeans includes a bearing member mounted in said driven member forsubstantially radial movement, and also includes biasing means urgingsaid bearing member against said rim.

8. A mechanism as defined in claim 7, wherein said intermediate memberembraces said driven member.

References Cited UNITED STATES PATENTS 2,896,873 7/1959 Mageoch 24267.42,906,184 9/1959 Hennig et a1. 74-405 X 3,073,542 1/1963 Kaashoek242-675 LEONARD H. GERIN, Primary Examiner US. Cl. XR, l92--41;242--67.5

